Various techniques are known for embedding collateral information in images, in files of text, in audio information and in other types of digital information. Digital watermarking (which are a particular type of steganographic data encoding) are one way of imbedding collateral information in digital files. There are many types of digital watermarks. For example, prior application Ser. No. 09/127,502, filed Jul. 31, 1998, now published as U.S. Pat. No. 6,345,104 and WO0007356, (which is assigned to the assignee of the present invention) shows a technique by which very fine lines can be printed on a medium to slightly change the medium's apparent tint, while also conveying digital data. application Ser. No. 09/074,034, filed May 6, 1998, now published as U.S. Pat. No. 6,449,377 and WO 9953428, details how the contours of printed imagery can be adjusted to convey digital data. Issued U.S. Pat. No. 5,850,481 details how the surface of paper or other media can be textured to convey optically-detectable binary data. Issued U.S. Pat. Nos. 5,862,260, 5,841,886 and 5,809,160 detail various techniques for steganographically encoding photographs and other imagery. There are a great man other patents and a large body of literature which describe various other watermarking and steganographic techniques.
The technology and science for collecting user preferences using the internet and other data gathering mechanisms is also well developed. For example U.S. Pat. Nos. 5,918,014 and 5,933,811 and PCT publication WO 00/38074 describe systems that collect data concerning users and which then provide to the users advertisements directed to what the system decides is their particular interests and preferences. As used herein the term “user characteristics” means any information about a user's characteristics or preferences such as the type of information discussed in the article “Privacy 2000 In Web We Trust” published in the magazine “PC World”, June 2000, pages 103 to 108.
Systems such as the system described in application Ser. No. 09/571,422 filed May 15, 2000, now U.S. Pat. No. 6,947,571, utilize collateral data stored in printed images to carry a URL (Universal Resource Locator) address (or a dynamic index to a database entry storing such addresses). When a user of the system directs a camera at an image containing the collateral data, the user's web browser is directed to a particular web site.